The invention relates to a monitoring system for leakage of fluid in a pressure supply system and provides a means of closing the fluid outlet and preventing damage. The types of pressure supply systems for which the invention is intended are water supply to buildings, water and gas-based fire-fighting sprinkler systems and gas supply for instance to hospitals. In other words, the system can be used for systems containing liquids (water, oil) and gases (fire-fighting gases, pneumatic gases). In the presentation of a preferred embodiment, the type used on water supply to buildings will be used as an example.
Damage caused by water leaks from water supply systems in buildings represents considerable loss and expenses to owners and insurance companies. Water leaks which are detected by a person shortly after occurring can be stopped and the damage limited. Minor water leaks occurring in pipework running inside walls, ceilings or under floors are more difficult to detect and the resulting damage is therefore more extensive. Very small leaks may not be detected at all before the building materials have been invaded by fungus and mould or have started rotting. Major leaks may not even be detected before a certain time if the residents of the house are absent for a long period of time.
Damage caused by water leaks is often extensive because the water penetrates insulation material. In such cases, the only way to eliminate the moisture is to open the building structure, remove the wet insulation and replace it with new material. This results in extensive and costly repair work.
There exist only a few systems on the market today which can limit the damage caused by water leaks. Such safety systems are, in Norway, approved by the Norwegian Building Research Institute. Safety systems are divided into two main groups: active and passive systems. Passive systems monitor leaks and, when such a leak occurs, they give an auditory signal but take no action toward limiting the damage. Such systems are therefore not suitable for limiting damage when the building is empty and no one is on the premises to cut off the water supply.
Active systems detect leaks and cut off the water supply and are, in this respect, much more efficient at limiting water-related damage.
The active systems are classified into two categories: category 1 which detect and close off leaks in pipework and in household appliances, and category 2 which are active only in regard to household appliances. Until recently there was only one approved system in category 1 on the Norwegian market. This system consisted of a water gauge, a shut off valve and an electronic control device. When the system was installed in a house, information on the daily water consumption was programmed in the control device, based on the anticipated daily water consumption for the whole house. In the event of a leak, the system would at worst allow the water to continue leaking until the equivalent of one programmed day""s consumption had leaked out. In a house where the residents are absent on holiday for instance, such a system would allow an unnecessary quantity of water to leak out before the supply is cut off. This type of system is rather inappropriate and unsuitable for reducing damage caused by water leaks to a minimum.
In category 2 of active systems, several systems are available which operate in about the same manner. These systems consist of a central control unit which is installed in the vicinity of the water intake to the building and a controllable shut off valve. From this control unit and to each of the household appliances or places where monitoring of possible water leaks is requiredxe2x80x94for example, on the floor close by a dishwasher, a washing machine built-in a sink unit or the likexe2x80x94are installed electrical connections to water sensors which detect any water spill thus enabling the control unit to cut off the water supply by closing the shut off valve.
None of the described or known water-leak detection systems can monitor all the parts of the pipework in a water supply system, detect water leaks and immediately cut off the leak.
The object of the system of the present invention is to provide a solution which takes the following requirements into account:
register the slightest leak in any part of the water supply system in a building, whether on the hot or cold water supply,
cut off the intake of water from outer sources very shortly after the leakage has been registered,
control the intake from the water main and close off this intake when there is no consumption of water,
convey to the user the necessary information about the leak,
the system must be reset before water can be drawn again.
The above is achieved by closing off the intake of fluid into the pressure system and the pressure drop signal which is registered on opening a faucet or a valve is designed to open the intake if the pressure in the distribution line downstream of the intake exceeds a certain threshhold value.